Momentum is a vector quantity that describes the motion of an object and is defined as the product of its mass and velocity. It is a measure of the amount of motion contained in an object.

The SI (International System of Units) unit of momentum is the kilogram meter per second (kg m/s). In the CGS (centimeter-gram-second) system, the unit of momentum is the gram centimeter per second (g cm/s). Here are the conversions between the SI and CGS units of momentum:

- 1 kg m/s = 1000 g cm/s

- 1 g cm/s = 0.001 kg m/s

Additionally, in the MKS (meter-kilogram-second) system, the unit of momentum is the kilogram meter per second (kg m/s), which is the same as the SI unit.